Higher order parametric X-ray spectra in mosaic graphite and single silicon crystals

We have observed up to eight orders (n) in the spectra of parametric x-radiation, in the range 5-40 keV, produced by the interaction of a 90 Mev electron beam with mosaic graphite and 90 and 35 Mev beams with single silicon crystals. The measured yields and intensity ratios, I(2)/I(n= I), in graphite are not in agreement with the theory of PXR for mosaic crystals. In comparison, the yield and ratios of intensities in silicon are close to the predictions of PXR theory for perfect crystals. The bandwidths of spectral lines measured in both silicon and graphite are in good agreement with theoretical predictions, and are determined by the angular field of view of the detector.U.S. Department of EnergyDNANaval Postgraduate SchoolContract No. DE-FG03-91ER8109

A concept for Z-dependent microbunching measurements with coherent X-ray transition radiation in a sase FEL

We present an adaptation of the measurements performed in the visible-to-VUV regime of the z-dependent microbunching in a self-amplified spontaneous emission (SASE) free-electron laser (FEL). In these experiments a thin metal foil was used to block the more intense SASE radiation and to generate coherent optical transition radiation (COTR) as one source in a two-foil interferometer. However, for the proposed x-ray SASE FELs, the intense SASE emission is either too strongly transmitted at 1.5 Angstrom or the needed foil thickness for blocking scatters the electron beam too much. Since x-ray transition radiation (XTR) is emitted in an annulus with opening angle 1/g = 36 mrad for 14.09-GeV electrons, we propose using a thin foil or foil stack to generate the XTR and coherent XTR (CXTR) and an annular crystal to wavelength sort the radiation. The combined selectivity in angle and wavelength will favor the CXTR over SASE by about eight orders of magnitude. Time-dependent GINGER simulations support the z-dependent gain evaluation plan

A concept for Z-dependent microbunching measurements with coherent X-ray transition radiation in a sase FEL

We present an adaptation of the measurements performed in the visible-to-VUV regime of the z-dependent microbunching in a self-amplified spontaneous emission (SASE) free-electron laser (FEL). In these experiments a thin metal foil was used to block the more intense SASE radiation and to generate coherent optical transition radiation (COTR) as one source in a two-foil interferometer. However, for the proposed x-ray SASE FELs, the intense SASE emission is either too strongly transmitted at 1.5 Angstrom or the needed foil thickness for blocking scatters the electron beam too much. Since x-ray transition radiation (XTR) is emitted in an annulus with opening angle 1/g = 36 mrad for 14.09-GeV electrons, we propose using a thin foil or foil stack to generate the XTR and coherent XTR (CXTR) and an annular crystal to wavelength sort the radiation. The combined selectivity in angle and wavelength will favor the CXTR over SASE by about eight orders of magnitude. Time-dependent GINGER simulations support the z-dependent gain evaluation plan

Optimisation opportunities for HPGR circuits

Based on a thorough review of the Mogalakwena North Concentrator of Anglo Platinum Operations, a wide range of issues were identified that form bottlenecks to the operation. In order to address these, a series of surveys were conducted and the entire dry circuit modelled in detail. From this a full simulation of the plant has been developed, this includes updated models of the HPGR, crusher, bins and screens. These have been implemented in the researchers MDK version of JKSimMet and in a prototype dynamic simulator based on the Matlab Simulink software.The observations, measurements and simulations have provided guidance and quantified the influence of proposed circuit modifications. Based on these a number of upgrades are being planned aimed at ensuring full utilisation of the installed equipment. The circuit demonstrates a potential expansion of over 30% through minor improvements and 70% with the addition of some strategic equipment

Developments in on-line, electron-beam emittance measurements using optical transition radiation techniques

We have developed image analysis software to facilitate the analysis of optical transition radiation (OTR) patterns generated by the electron beam from the Los Alamos free-electron laser facility. The software can be used for beam alignment, beam profile and angular divergence measurements, and the programs run on an IBM AT microcomputer. The programs and their use are described and some results shown. 2 refs., 17 figs